Frequently Asked Questions - Traffic Data
What is a traffic count?
A traffic count is a count of traffic on State Routes, major county roads, and major city streets. All traffic counts represent a typical 24 hour period, counting traffic in each direction of traffic flow.
How do I get a traffic count?
Contact Georgia's Office of Transportation Data (OTD): OTD Inquiry Form or (Fax) 770-986-1448, or select "Georgia's State Traffic And Report Statistics (STARS)" or "Georgia ATR Traffic Data Reports" on the Transportation Statistics and Reports page.
What is the standard business hours of Georgia's Office of Transportation Data?
Monday-Friday 8:00 AM - 4:45 PM (EST).
What happened to I-Map?
Georgia's State Traffic And Report Statistics (STARS) has replaced I-Map. Select "Georgia's State Traffic And Report Statistics (STARS)" on the Transportation Statistics and Reports page.
What are the most recent traffic counts available?
The most recent traffic counts are available for 2007. Select "Georgia's State Traffic And Report Statistics (STARS)" or "Georgia ATR Traffic Data Reports" on the Transportation Statistics and Reports page.
When will the new traffic counts be published?
Normally, traffic counts are available by the spring of each year.
What does AADT stand for?
AADT stands for Annual Average Daily Traffic.
Does Georgia's Office of Transportation Data provide traffic speed data?
No, currently we do not provide traffic speed data.
Why is there a traffic counter on my street?
The state of Georgia is required to collect a certain amount of traffic counts on the roadways throughout the state. The counts are compiled and reported in federal reports prepared each year. These reports help the federal government decide how much money the state of Georgia will get for transportation and road infrastructure projects each year.
What are the current traffic conditions?
Contact Georgia's Traffic Management Center (TMC): (404) 624-1300, or visit Georgia's Navigator page.
In regards to county traffic data on your website, what does the "Est." and "AVG" mean?
If the column indicates 'AVG', there are two or more data items that have been taken into account. If the column indicates 'EST', the data is estimated based upon previous year(s) data.
Where can I get historical traffic information?
Contact Georgia's Office of Transportation Data: (Fax) 770-986-1448 or complete the OTD Inquiry Form.
What is the difference between AADT and VMT?
One of the key variables in determining the VMT (Vehicle Miles Traveled) is the AADT (Annual Average Daily Traffic). The VMT is calculated by multiplying the AADT for a given road section times the length of the road section. This calculated value is the VMT for this road section.
To accumulate this figure by route or to summarize for reporting purposes, this number is accumulated for every road section.
For Example: You want to calculate the VMT for I-75. Since I-75 is a long route (355 miles) we know that it will have many road segments and AADT values to consider. For each road segment, the section length is multiplied by the applicable AADT for that segment and is accumulated. After this calculation has been performed on all of the road segments for I-75, the accumulated value is the VMT for I-75. In 2003, the Daily Vehicle Miles Traveled on I-75 was 29.2 million. This same calculation process is performed on all road segments for the State and is typically "rolled up" by functional classification road system, by county, by State, or any other jurisdiction or stratification that is available in our database.
Where can I find Mileage/VMT reports?
Select "Georgia ATR Traffic Data Reports" on the Transportation Statistics and Reports page.
What are traffic counts used for?
Traffic counts are used to determine traffic patterns and flows for modeling purposes. They are also used in developing plans to aid in alleviating congestion with the construction of new routes or alternate designs.
For example, Georgia's Office of Materials Research uses a combination of truck percentages and Annual Average Daily Traffic (AADT) data to develop factors that assess the deterioration of pavement.
Georgia's Traffic Operations Office uses the volume data for safety related purposes (calculating crash rates and addressing safety issues).
The Federal Highway Administration (FHWA) requires every state to submit an annual Highway Performance Monitoring System (HPMS) report containing traffic count data, physical characteristics, and other pertinent road data. This submittal is used in legislation, and to determine State funding of highway and road projects.
Who uses traffic data?
Customers of the data include transportation planning professionals, educational institutions, design engineers, contractors, real estate agencies, private companies, and other government agencies. The data is used on national, state, and local levels for planning, modeling, allocation of funding, and informational purposes. Select "Designer's Manual - Georgia Highway System Administrative Review" on the Transportation Statistics and Reports page for general uses of traffic data.
How often do you conduct traffic counts?
There are two types of traffic counts, portable and permanent.
Portable traffic collection devices are placed on all types of road systems to collect traffic data during a typical 48 hour period. As of January 2005, there is an estimated 17,500 portable traffic count location sites in Georgia.
Permanent Automatic Traffic Recorder (ATR) sites count traffic seven days a week, 24 hours a day, 365 days a year. There is an estimated 354 permanent traffic count location sites.
Portable and permanent traffic counts are collected by our Road Data Collection Branch.
How do you determine on which streets to conduct traffic counts?
Roads are designated as State Routes (SR), County Roads (CR), and City Streets (CS), depending upon ownership.
The roads are divided into sections designated with Traffic Count (TC) numbers. Each TC number has an Average Annual Daily Traffic (AADT) count.
In order to ensure the most reasonable traffic data is reported in the long term, Georgia's Office of Transportation's portable traffic count program collects data on an annual cycle in which data is collected at each station for a 48-hour period Portable data is collected at locations that are distributed among the following stratification groups, known as Functional Classification Groups. Select "Highway System Status Map Series on the Maps page.
How do you determine when to conduct the counts (for example, do you typically do them during the summer or does the time vary?)
Permanent traffic data collection devices are used to continuously collect traffic data.
Portable traffic data collection devices are used to collect the traffic counts during typical travel conditions (not on holidays or weekends).
The raw hourly counts are adjusted by seasonal, daily, and axle factors to determine the Annual Average Daily Traffic (AADT).
Seasonal factors are developed according to 11 factor groups and calculated by dividing the average AADT by the monthly AADT for each location.
Daily factors are calculated by dividing the average AADT by the daily AADT. Factors are based on data provided by Automatic Traffic Recorders (ATR).